1. Field of the Invention
The present invention relates to an injector for liquid medicine and, more particularly, an injector which enables to continually administer a little dose of a liquid medicine after priming. The injector of the present invention is useful for administration of an additional medicine in midstream of administration of one medicine and for administration of a medicine which may cause infection of an operator during mixed administration of different medicines such as antitumor agents.
2. Background Art
When performing administration of a liquid medicine with an infusion set or a catheter, it is frequently necessary to administer another medicine in midstream of administration. Such operations are required, for example, in administration of contrast media, hormone preparations, peptide preparations, antitumor agents, vitamin preparations, etc. This is generally done using a prefilled syringe, i.e., a syringe with a liquid medicine previously charged therein.
So far, such mixed administration has been carried out using a three-way stopcock or a Y-shaped tube to change over route of administration.
However, use of the three-way stopcock or Y-shaped tube may cause leakage of the charged medicine at the time of connection of the prefilled syringe or priming operation. In particular, in case of medicines such as antitumor agents which are high in carcinogen, the leakage of such a medicine may causes health problems of the operator. Further, the administration of a little dose of expensive medicine is difficult to operate and makes it difficult to perform effective administration since the medicine may be diluted with other medicine. In addition, there is a problem such that the medicine is remained in route of administration.